1. Field of the Invention
The present invention relates to an antenna, and more particularly to an multi-frequency antenna having wider range of frequency band.
2. Description of Prior Art
Wireless communication devices, such as cellular phones, notebook computers, electronic appliances, and the like, are normally equipped with an antenna for working in WLAN (Wireless Local Area Network) that serves as a medium for transmission and reception of electromagnetic signals, such as date, audio, image, and so on. However, more and more people dissatisfy their electronic devices only work in WLAN (Wireless Local Area Network). Making the portable electronic devices working in WWAN (Wireless Wide Area Network) or GPS (Global Positioning System) is a purpose of the many people.
In recent years, WLAN adopts two key technical standards of Bluetooth and Wi-Fi. Bluetooth works in 2.4 GHz, and Wi-Fi works in 2.4 GHz and 5 GHz. However, WWAN adopts three technical standards of GSM (Global System for Mobile Communication), GPS (Global Positioning System) and CDMA (Code Division Multiple Access). Operating frequency bands of the GSM are 900/1800 MHz, and operating frequency band of the GPS is 1.575 GHz. CDMA includes three kinds of technical standards: CDMA2000, WCDMA and TD-SCDMA. Operating frequency bands of the CDMA2000 are 800, 900, 1700, 1800, 1900, and 2100 MHz. Operating frequency bands of the WCDMA are 1800, 1900, and 2100 MHz. Operating frequency bands of the TD-SCDMA are 900, 1800, and 2100 MHz.
Taiwanese patent No. 1254493 discloses a multi-band antenna including two radiating elements for working 1800 MHz frequency band and 900 MHz frequency band.
However, the multi-band antenna has narrower range of frequency band, and is not capable to cover all frequency bands of WWAN.